As a candidate, Barack Obama promised to withdraw from Iraq, “finish the fight against al-Qaida and the Taliban,” shut down Gitmo and break through the impasse with Iran. But as president, Obama is learning that conducting U.S. foreign policy is far more difficult than simply critiquing it. As a consequence, on the central foreign policy and national security issue of the day -- the global struggle against Islamic terrorists and their patrons and partners -- there is far more common ground between Obama and former President George W. Bush than Obama’s supporters expected, and less change than his opponents feared. To be sure, this emerging continuity is overshadowed by Obama’s rhetoric, sprinkled with references to “the failed policies of the previous administration.” And to be sure, there are differences in other areas of foreign policy (the divergent approaches to Russia, missile defense and Israel-Palestine, for example). But in the fight against Islamic terrorists, actions speak louder than words.

Consider the Obama administration’s policies in Yemen and the Afghanistan-Pakistan theater. Obama will never admit it, but on these two fronts, he is carrying out a key element of the Bush Doctrine -- namely, that the U.S. will target the places where terrorists find refuge and support any governments that are too weak to wage the battle alone.

Hence, the U.S. is striking at terrorists in Yemen -- Obama has ordered missile attacks against al-Qaida camps, allowed for the sharing of satellite imagery and other intelligence, and expanded U.S.-Yemeni military cooperation -- while sending increasing amounts of aid to bolster the country’s embattled government. CENTCOM commander Gen. David Petraeus reports that counterterrorism funding for Yemen will more than double in 2010, to around $150 million.

In the Afghanistan-Pakistan theater, it pays to recall that Obama’s controversial-yet-effective “drone war” actually began under Bush. In addition, Bush administration officials -- among them, Vice President Richard Cheney -- say that the Afghanistan-Pakistan plan announced by the Obama administration in early 2009 was largely developed in the final months of the Bush administration and handed off to Obama’s national security team. “The new strategy they embraced in March, with a focus on counterinsurgency and an increase in the numbers of troops, bears a striking resemblance to the strategy we passed to them,” Cheney has observed.

That the handoff wasn’t fumbled is in large part because Obama hired Bush’s defense secretary, Robert Gates, who helped plan the revised mission for Afghanistan-Pakistan and carried out the successful surge strategy in Iraq.

That brings up another reason for continuity between Bush and Obama on national security: Americans may change presidents in the middle of a war, but they seldom abandon that war’s objectives or even the means to those objectives.

America’s postwar history bears out this simple truth. Dwight Eisenhower might not have thrown around the words “the Truman Doctrine,” but he followed the general direction carved out by Harry Truman, as did subsequent presidents for the balance of the Cold War. Richard Nixon went on waging Lyndon Johnson’s war in Vietnam for four long years. Ronald Reagan’s military build-up actually began during Jimmy Carter’s presidency. The elder George Bush was pounded for doing nothing in Bosnia by Bill Clinton, who proceeded to do nothing in Bosnia for nearly three years.

Likewise, Clinton followed the elder Bush’s hundred-hour war against Saddam Hussein with a “low-grade war” against Hussein that lasted for eight years. The younger Bush took down Saddam’s regime and began the process of planting a free government in Iraq. And now Obama, who once proposed a plan to begin withdrawing U.S. forces from Iraq “no later than May 1, 2007,” is continuing that very process.

In fact, it was the Bush administration’s revamped counterinsurgency strategy in Iraq that brought about a more stable security environment and enabled Bush to begin the withdrawal promised by Obama. Hopefully, Obama will resist the temptation to speed up the drawdown before Iraq’s government and security forces are ready.

If, in Iraq, Obama is jumping off from where Bush finally landed, on Iran, Obama has now landed where Bush ended up stuck: frustrated by Iran’s intransigence, Russia and China’s gamesmanship, and the U.N.’s inertia.

Despite Obama’s overtures, Iran has remained defiant. As French President Nicolas Sarkozy detailed when evidence of a secret Iranian nuclear-fuel manufacturing plant came to light in September 2009, “Since 2005, Iran has violated five Security Council resolutions . . . An offer of dialogue was made in 2005, an offer of dialogue was made in 2006, an offer of dialogue was made in 2007, an offer of dialogue was made in 2008, and another one was made in 2009 . . . What did the international community gain from these offers of dialogue? Nothing. More enriched uranium, more centrifuges.”

To a certain degree, continuity has been forced upon the Obama administration by the behavior not only of Iran, but also North Korea, which tested missiles and a nuclear weapon during Obama’s first year in office, just as it had during the Bush administration.

Finally, Gitmo’s critics -- Obama chief among them -- have variously labeled the detention facility a stain on America, a black mark, a cancer. Bush himself wanted to close Gitmo but couldn’t find a way to do so that would ensure the safety of the American people and the continued detention of those committed to killing them.

Obama made his position clear throughout the campaign and etched it into history on Jan. 22, 2009, just two days into his administration, when he issued a presidential directive to close Gitmo “no later than one year from the date of this order.” Of course, Obama’s deadline has come and gone. In other words, even this policy change highlights the continuity between Bush and Obama, albeit in an unintended way.

Some say the high ground is eroding beneath Obama’s feet every day that Gitmo remains open. To the contrary, concerning Gitmo and other issues, Obama is learning that the high ground disappears when the campaign ends and governing begins, leaving a new president on common ground with his predecessor.